The present invention relates to a piezoelectric vibrator unit in which internal electrodes are stacked in parallel with the expansion/contraction axis, and more particularly to the structure of internal electrodes, and also to an ink jet recording head.
As disclosed in Japanese Patent Publication No. 4-1052A, in an ink jet recording head using a piezoelectric vibrator of the longitudinal vibration mode, an elastic plate is placed via a small gap on the back face of a nozzle plate in which plural nozzles are opened, and piezoelectric vibrators having the piezoelectric constant d31, which are obtained by dividing so as to correspond to respective pressure generating chambers of a channel substrate, abuts against the back face of the elastic plate. Ink in a reservoir is guided into the pressure generating chambers via associated ink supply ports, and the ink is then pressurized by the piezoelectric vibrators which are driven by a recording signal, thereby causing the ink to be ejected from the nozzle orifices.
As disclosed in Japanese Patent Publication No. 7-195688A, for example, such a piezoelectric vibrator is configured in the following manner. It is prepared a single piezoelectric diaphragm in which common electrodes and internal individual electrodes are alternately stacked on each other while sandwiching a piezoelectric material therebetween. In the piezoelectric diaphragm, the internal common electrodes are exposed from a rear end face on the side of the fixed end, and the internal individual electrodes are exposed from a front end face on the side of the free end. The piezoelectric diaphragm is divided such that dummy piezoelectric vibrators are arranged in both sides thereof, and driving piezoelectric vibrators are formed into a comb-like shape in the central portion thereof so that their non-vibrating regions are continuous.
The internal individual electrodes are connected to a segment electrode which elongates from the front end face to a top face of a non-vibrating region, and the internal common electrodes to a common electrode which elongates from the rear end face to the top face of the non-vibrating region. A driving signal is supplied to the segment electrode and the common electrode via a flexible cable.
As described above, the external electrodes, which constitute the segment electrode and the common electrode, are formed in an L-like shape on the two faces, i.e., the end faces and the top face. Therefore, there arise problems in that conductive failure easily occurs in a conductive layer in the interface between the end face and the top face, and hence the formation of the conductive layer requires much labor, and that corner edges tend to be broken and a connection failure thereby occurs, thereby lowering the production yield.